Terrain Resilient Wheel Maintaining a Uniform Elevation

ABSTRACT

A wheel includes a central hub and a flexible rim. A drive band configuration including a plurality of flexible bands extends as spokes from the central hub to the rim. The hub and band configuration cause the rim to flex toward and away from the hub as the wheel moves.

BACKGROUND

Wheels and tracks are a primary source of propulsion and/or motion for avariety of vehicles and applications. Conventional wheels and trackstend to churn the terrain they move over. Wheel designs thus couldbenefit from a greater capability to adapt to the terrain whilemaintaining stability and forward progress.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, the same reference numbers and acronyms identifyelements or acts with the same or similar functionality for ease ofunderstanding and convenience. To easily identify the discussion of anyparticular element or act, the most significant digit or digits in areference number refer to the figure number in which that element isfirst introduced.

FIG. 1 illustrates a tread and rim that form part of a terrain adaptablewheel.

FIG. 2 illustrates a configuration of drive bands that may be coupled tothe axis mounts.

FIG. 3 illustrates construction of a wheel hub.

FIG. 4 illustrates a drive gear that may be fitted to the central axisfor higher torque applications.

FIG. 5 illustrates a completed wheel with four hub components.

FIG. 6 illustrates a wheel having six hub components and utilizing sixbands.

FIG. 7 illustrates a gear driven six spoke hub design.

FIG. 8 illustrates a hybrid design employing bands with gear tracks andbands without gear tracks.

DETAILED DESCRIPTION Preliminaries

References to “one embodiment” or “an embodiment” do not necessarilyrefer to the same embodiment, although they may. Unless the contextclearly requires otherwise, throughout the description and the claims,the words “comprise,” “comprising,” and the like are to be construed inan inclusive sense as opposed to an exclusive or exhaustive sense; thatis to say, in the sense of “including, but not limited to.” Words usingthe singular or plural number also include the plural or singular numberrespectively, unless expressly limited to a single one or multiple ones.Additionally, the words “herein,” “above,” “below” and words of similarimport, when used in this application, refer to this application as awhole and not to any particular portions of this application. When theclaims use the word “or” in reference to a list of two or more items,that word covers all of the following interpretations of the word: anyof the items in the list, all of the items in the list and anycombination of the items in the list, unless expressly limited to one orthe other.

Overview

Embodiments of a wheel are described, having a load-bearing (central)axis that shifts horizontally in a uniform horizontal plane as it movesacross the terrain. The wheel includes a central hub and a flexible rim.A drive band configuration for the wheel includes flexible bandsextending as spokes from the central hub to the rim. The hub and bandconfiguration are configured to cause the rim to flex toward and awayfrom the hub as the wheel moves. The wheel thus tends to unfold over theterrain, rather than churn the terrain as would a conventional wheel.

Detailed Descriptions of Particular Embodiments

FIG. 1 illustrates a tread 104 and rim 106 that form part of a terrainadaptable wheel. Axle mounts 102 may be attached to the rim 106, forexample using mounting holes 108 (e.g., via machine screws through themounting holes). The tread 104 is illustrated as a caterpillar type, butmay in fact be any tread suitable to the vehicle and the terrain. Therim 106 may be metal, plastic, or other suitable materials. Likewise,the tread 104 may be rubber, metal, plastic, or any suitable material.Multiple axle mounts 102 may be fixed to the rim 106 at multiplelocations. The ends of the rim 106 are illustrated with a slight gapbetween them, but would typically be joined together. In some designsthe rim 106 may be constructed using two strips of clock spring, fusedto a single strip of rubber tire.

Typically, the axle mounts 102 will be spaced at equal intervals aroundthe circumference of the rim 106. Embodiments including four and sixaxle mounts 102 will be described, although other numbers of axis mountsare also possible depending upon requirements of the particularimplementation.

FIG. 2 illustrates a configuration of drive bands 210 that may becoupled to the axle mounts 102. The drive band configuration 210 iscomprised of multiple drive bands 204. Each drive band 204 may be formedto flex along a long axis of the band 204 and may be substantially rigidto both sheer and twisting force along axes perpendicular to the longaxis. Example materials for the band 204 are carbon steel, stainlesssteel, other metals and alloys, and plastic. The bands 204 are joinedtogether at each end using couplers 202. Each coupler 202 couples ajoint of the band configuration 210 to a axis mount 102 via an insertedaxle 208. The axle 208 is inserted through the coupler 202 and throughthe axle mounts 102 on either end of the axle 208. A flexible cover 206(e.g., a cylindrical polyethylene cover) may be fitted over each coupler202 to reduce friction of the coupler 202 against the axle mounts 102(give example materials for cover 206). Before inserting the axle 208,the coupler 202 is rotated so that once the axle 208 is inserted, a gap212 in the coupler 202 is rotated 180 degrees from a gap 214 in the axle208. This secures the joint between drive bands 204 and also allows forsome limited motion of the joint within the coupler 202 once it iscoupled to the axis mount 202 during rotation of the wheel.

One design includes a drive band configuration constructed from fourbands joined at their ends into a closed four-sided periphery. Anotherdesign includes a drive band configuration constructed from six bandsjoined at their ends into a closed six-sided periphery. Designsincluding n numbers of bands formed into closed n-sided peripheries(eight, ten, etc.) are also possible.

FIG. 3 illustrates construction of a wheel hub 310. The wheel hub 310 isconstructed from a plurality of hub components 302. Hub components 302are symmetrically positioned around a center axle 308. Each hubcomponent 302 may comprise ends 304 having a diameter (circumference)that is larger in relation to an inner circumference of the hubcomponent 302. In some designs (e.g., four spoke designs), the ends 304are separate elements rotationally coupled the hub component 302. Inthese designs, as the rim 106 moves inward toward the hub 310, itcontacts the ends 304 of the hub components 302, and the ends 304 rotateagainst the rim 106 as the wheel turns. The ends 304 rotate against therim 106 in an opposite direction of rotation of the inner diameter 314against the bands 204. This provides stability to the flexible rim 106without decreasing terrain flexibility. Thus each hub component 302, asa unit including its ends 304, simultaneously rotates both clockwise andcounterclockwise as the wheel turns.

The band configuration 210 is compressed inwardly near the center ofeach band 204 and compressed to fit between the center axle 308 and eachof the hub components 302. The result is that each spoke from the hub310 to the rim 106 comprises two bands 204 pressed together. Couplers306 are fitted over both ends of the hub 310 and retain the bandconfiguration 210 within the hub 310 and retain the hub components 302in a symmetrical configuration. Power from a drive axle (e.g. axle 308)may be transferred to the hub 310 via the couplers 306 in some designs.

In some implementations, particularly those that use a coordination gearon the center axle 308, some hub components have a first innercircumference 314, and others have a second, smaller circumference(refer to FIGS. 7 and 8). The smaller circumference components are usedas spacers to limit the rim 106 minimal distance from the center axle308 as the wheel turns and to hold the bands 402 snug with component 714and gear 406.

FIG. 4 illustrates a coordination gear 406 that may be fitted to thecentral axle 308. The gear 406 coordinates motion of the bands 402. Eachband 402 of the band configuration 210 may comprise a gear track 404 tomate with teeth of the coordination gear 406. In models employing acoordination gear 406, each spoke from the hub 310 to the rim 106 maycomprise only a single band 402. The gear 406 rotates freely upon theoutside of the central axle 308 of the wheel, coordination motion of thebands 402.

FIG. 5 illustrates a completed wheel with four hub components 302. Thebands 204 are compressed between the central axle 308 and the hubcomponents 302. Each band is coupled to the rim 106 by axle mounts 102.As the wheel turns, the ends of the bands 204 pivot around the axis 208which couples the bands 204 to the axle mounts 102. The bands 204 areextended away from the hub 310 or are drawn toward the hub 310,depending on the position of the wheel, giving the rim 106 and tread 104a peripheral shape that varies according to the position of the wheeland the topography under the wheel. The rim 106 and tread 104 yield andflex according to the terrain, thus shifting mass of the wheel and anyassociated vehicle more directly over a force normal to the surfacebeing traversed. In this manner, the wheel adapts efficiently to theterrain it is traversing.

A wheel employing a hub design in accordance with these features andprinciples swivels between a plurality (e.g., two) pivot points of therim 106 as it rotates. The hub oscillates between the ends of theflexible spokes. Each spoke exhibits a cycle of advancing forward of thehub, receding inward toward the hub, and advancing rearward from thehub. The spokes act in unison to deflect the rim in a manner thatcontributes to gripping the terrain.

In the case of a four-spoke wheel, the bottom spoke, orthogonal to theground, recedes inward towards the hub. This causes the top spoke toalso recede inward. The other two spokes (horizontally positioned)advance outward providing indirect load-support for the hub.

The four-spoke wheel design employs hub components 302 comprising aninner diameter (circumference 314) and a larger, outer diameter 304 thatrotates independently of the inner diameter 314. The outer diameter 304of the components 302 may rotate against the rim 106 as the wheel turns,in an opposite direction of rotation as the rotation of the innerdiameter 314. The components 302 may be constructed from an innerrotating member with washers rotationally coupled to the ends.

The particulars of the motion and shape of the rim may vary betweendesigns that employ the features and principles described herein,depending upon design details of the implementation and components.

FIG. 6 illustrates a wheel having six hub components 302 and utilizingsix bands 204. As the wheel turns, the relative distance of the rim 106from the central axle 308 varies according to the topography of thesurface. The wheel's mass is efficiently shifted more directly over theforce normal to the surface being traversed.

The central bottom spoke recedes inward which causes the two adjacentspokes to advance outward at an acute angle to the terrain. Thisdeflection results in the hub being supported by three spokes and notjust a single spoke, as is the case of a four-spoke wheel.

The particulars of the motion and shape of the rim may vary betweendesigns that employ the features and principles described herein,depending upon design details of the implementation and components.

Designs comprising six, eight, and higher numbers of spokes need notcomprise hub components 302 with a larger, independently-rotating outerdiameter (as do certain four spoke designs, e.g. FIG. 5). Two spokesadjacent to the bottom, central, orthogonal spoke advance outward at anacute angle to the terrain during rotation, maintaining the hub is in astate of equilibrium, balanced by opposing forces of the threesupporting spokes. In these designs, the hub components 302 do not rideupon (rotate against) the rim 106 of the wheel.

FIG. 7 illustrates a gear coordinated six spoke hub design. The hubcomprises bands 402 comprising gear tracks, as illustrated, for examplein FIG. 4. A gear 406 coordinates motion of the bands 402. Each end of aband 402 forms a spoke of the hub. Thus, three bands are sufficient toconstruct a six-spoke hub in the gear coordinated design. Bands 402 rideupon an outer circumference 714 of hub components 702. The outercircumference 714 of hub components 702 allows the gear tracked band totightly arc component 702. Couplers 710 prevents lateral motion of thebands 402.

Spacer hub components 708 are provided to fit in a space between thelarger diameter hub components 702 when the hub is assembled. Spacers708 fill in these gaps and retain the bands 402 in the hub and againstthe gear 406. Couplers 710 may be employed to secure and properly orientthe hub components in relation to one another, serving a similar purposeof a component 306 in FIG. 3. Couplers 710 may also transfer power froma drive axle (e.g., 308) to the hub.

The spacers 708 do not necessarily have a smaller diameter than theinner circumference 712 or outer circumference 714 of the hub components702. Rather, the spacers 708 has a diameter selected to fit snuglybetween the bands 402 and the gear 406. For example, the circumferenceof the spacers 708 may be equal to the inner circumference 712 of thehub components 702 in some designs, or even larger in circumferencedepending on the configuration of the hub components 702.

FIG. 8 illustrates a hybrid hub design employing bands with gear tracksand bands without gear tracks. Elements of this hybrid model which arenot essential to the description are omitted from the drawing forclarity. The hybrid model may achieve benefits of both the model of FIG.3. and the gear coordinated model of FIG. 7. The hybrid model comprisesbands 402 with gear tracks, and smooth bands 204 lacking gear tracks.The bands 402 arc the outer circumference 714 of the hub components 702.The bands 204 arc the circumference of the spacer hub components 708.Each spoke of the hub comprises a portion of a band 402 and a portion ofa band 204. This makes the spokes stronger while still providing forpower transfer to the wheel rim using drive gear 406. Hybridimplementations comprise two bands per spoke (one gear tracked band, onesmooth band). The gear tracked band 402 engages the gear 406. The smoothbands 204 do not engage the gear 406 but instead arc the spacer hubcomponents 708. The spacer hub components 708 are sized to prevent thesmooth bands 204 from engaging the gear 406. The gear tracked bands 402coordinate motion of the spokes, while the smooth bands 204 eliminatechatter and add rigidity to the spokes. The spokes may attach to the rimmounts 202 where the ends of bands 402, 204 meet, as described forexample in conjunction with FIGS. 1 & 2.

The performance of a wheel employing designs in accordance with thedescribed principles/features may be adjusted by varying the “truecircumference” of the wheel. Extending the circumference of the wheel by4-10% beyond the “true circumference” may flatten the bottom side of thewheel, increasing its grip upon the terrain and its ability to rollsmoother upon flat, hard surfaces. The “true circumference” iscalculated from the diameter measured from center of the wheel hub tothe inside surface of the rim.

Uses of the rims/wheels in accordance with the describedprinciples/features include, by way of example, tracked vehicles, steepclimbing vehicles, rough or multi-terrain vehicles (e.g., military,amphibious, police, scientific), and robotic vehicles.

Comparison of Gear Driven and Non Gear-Driven Designs

Table 1 provides a comparison of implementations including only geartrack bands (A), only smooth bands (B), and both gear track and smoothbands (C). Each hub design comprises six spokes. Of course, other hubdesigns along the same principles may include a different number ofspokes.

TABLE 1 Comparison of hub designs A B C Number of bands 3 6 6 Number ofgear- 3 0 3 tracked bands Number of spokes 6 6 6 Bands per spoke 1 2 2Number of hub 3 (3 additional hub 6 6 components engaging components actas spoke bands spacers only) Number of spacer hub 3 (3 hub components 0(no spacer hub 3 (3 hub components components act as spacers only,components are used) act as spacers but also and do not engage engagespoke bands) spoke bands) Hub component type (1) Larger outer Uniformdiameter (1) Larger outer diameter with recessed diameter with recessedinner diameter inner diameter (2) Spacers with (2) Spacers with uniformdiameter uniform diameter smaller than outer smaller than outer diameterof (1) diameter of (1)

Implementations and Alternatives

For a predetermined overall hub size, a number of spokes (e.g., 4, 6, 8. . . ) may be chosen. Based on the hub size and number of spokes, asize of the hub components is determined to pressure fit against thecompressed band configuration while encircling the center axle.

As previously noted, in implementations that utilize a coordination gearand bands with gear tracks, a different sizing may be utilized for thehub components. For example, for a six spoke design, three hubcomponents may have a first diameter, and three hub components mayutilize a smaller or different diameter. Spacer components of adifferent diameter may act to keep the gear engaged against the geartracks on the bands and/or to maintain contact between the bands and thevarious hub components, while maintaining a consistent minimum distancebetween the rim 106 and the central axle (i.e., acting as spacers).

The hub components may be formed from a single piece of molded or milledmaterial, or assembled from multiple components (e.g., one component forthe band roller, others for the ends that roll against the wheel rim).The couplers and central axle may be a single piece, or assembled frommultiple components. The hub perimeter may have a non-circular crosssection (e.g., square, hexagonal, octagonal, etc). The hub componentsmay be implemented as ball or roller bearings, with or without anextended inner ring.

Particular embodiments of a wheel utilizing certain mechanicalfeatures/principles have been described. Variations of the describedembodiments utilizing these or similar features and principles will nowbe apparent to those having skill in the art in light of thisdisclosure. The range of wheel designs that the inventor has conceivedis not limited to the disclosed embodiments, but to all designs thatutilize the features and principles herein disclosed, and as set forthin the claims.

1. A wheel, comprising: a central hub; a flexible rim; a drive bandconfiguration comprising a plurality of flexible bands extending asspokes from the central hub to the rim; and the hub and bandconfiguration configured to cause the rim to flex toward and away fromthe hub as the wheel moves.
 2. The wheel of claim 1, further comprising:the central hub comprising a plurality of hub components symmetricallyarranged around a central axle; and the band configuration fitted tomove between the hub components and the central axle.
 3. The wheel ofclaim 2, further comprising: the central hub comprising exactly four hubcomponents.
 4. The wheel of claim 2, further comprising: the central hubcomprising exactly six hub components.
 5. The wheel of claim 2, furthercomprising: the central hub comprising exactly three hub components andthree spacers, the spacers having a smaller radius than the hubcomponents and configured to maintain a consistent minimum distance fromthe rim to the central axle.
 6. The wheel of claim 1, furthercomprising: the drive band configuration comprising bands joined attheir ends into a closed four-sided periphery.
 7. The wheel of claim 1,further comprising: the drive band configuration comprising bands joinedat their ends into a closed six-sided periphery.
 8. The wheel of claim2, further comprising: each hub component comprising raised endsconfigured to rotate against the flexible rim in a direction opposite adirection of rotation of a central portion of a corresponding hubcomponent against the band configuration.
 9. The wheel of claim 2,further comprising: each band comprising teeth to mate with a gearadjoining to the central axle.
 10. A wheel hub, comprising: a drive bandconfiguration comprising a plurality of flexible bands extending asspokes; and a plurality of hub components configured to cause the driveband configuration to flex toward and away from the hub as the hubrotates.
 11. The hub of claim 10, further comprising: the plurality ofhub components symmetrically arranged around a central axle; and theband configuration fitted to slide between the hub components and thecentral axle.
 12. The hub of claim 11, further comprising: exactly fouridentical hub components, and exactly four bands forming the drive bandconfiguration.
 13. The hub of claim 11, further comprising: exactly sixhub components, and exactly three bands forming the drive bandconfiguration.
 14. The hub of claim 11, further comprising: exactly sixhub components, and exactly six bands forming the drive bandconfiguration.
 15. The hub of claim 11, further comprising: exactlythree smooth bands and exactly three gear-tracked bands forming thedrive band configuration.
 16. The hub of claim 11, further comprising:exactly three hub components engaging the drive band configuration, andexactly three spacers, the . spacers configured to maintain a consistentminimum distance from the rim to the central axle.
 17. The hub of claim10, further comprising: the drive band configuration comprising bandsjoined at their ends into a closed n-sided periphery.
 18. The hub ofclaim 10, further comprising: the drive band configuration comprisingbands joined at their ends into a closed six-sided periphery.
 19. Thehub of claim 10, further comprising: the drive band configurationcomprising bands joined at their ends into a closed four-sidedperiphery.
 20. The hub of claim 10, further comprising: each hubcomponent comprising ends configured to rotate against the flexible rimin a direction opposite a direction of rotation of a central portion ofthe each hub component against the band configuration.
 21. A wheelcomprising a hub and spokes, the wheel configured such that the huboscillates between the ends of the spokes, with ach spoke exhibiting acycle of advancing forward of the hub, receding inward toward the hub,and advancing rearward from the hub as the wheel turns.